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Introduction Mycobacterium tuberculosis complex (MTBC), the primary cause of tuberculosis (TB), must be accurately identified to implement effective patient management and control strategies. Non-tuberculous mycobacteria (NTM) in suspected TB cases can result in erroneous diagnoses and needless treatment. Objective The study aimed to identify NTM in patients suspected of TB at a tertiary care hospital in central India using molecular methods. Methods This prospective study enrolled 400 suspected pulmonary and extra-pulmonary TB patients. Patients between the age of two to 90 years, of either gender, new and previously treated cases, Culture positive, patients with immune-compromised status, patients not responding to ATT, HIV positive and negative, and willing to give consent were included in the study. Liquid culture via the Mycobacterial growth indicator tube (MGIT) system was used to culture mycobacteria from clinical samples. The SD Bioline Ag MPT64 Test (Standard Diagnostics, South Korea) and in-house multiplex-PCR (mPCR) were used to differentiate between Mycobacterium tuberculosis complex and NTM species for the molecular identification of NTM GenoType® Mycobacterium Common Mycobacteria (CM) assay kit (HAIN Life Science, Nehren, Germany) was used following the manufacturer's protocol. Results Only 59/400 (14.7%) of the samples produced a positive result in MGIT culture, indicating the presence of mycobacteria, and 85.25% of the remaining 341 samples were negative for mycobacterial growth. Further investigation of these 59 cultures with mPCR and SD Bioline Ag MPT64 test showed that 12 (20.33%) cultures were determined to be NTM, while the remaining 47 (79.67%) were identified as MTBC. Genotype characterization with GenoType® mycobacterium CM assay kit revealed that five of the 12 NTM isolates (41.67%) showed patterns that were consistent with Mycobacterium (M.) fortuitum, three (25%) showed patterns that were consistent with M. abscessus, and four (33.33%) showed patterns that were consistent with M. tuberculosis. Conclusion These results emphasize the value of molecular methods for precisely identifying mycobacterial species, particularly in suspected TB cases. The high prevalence of NTM in positive cultures emphasizes the significance of differentiating between MTBC and NTM to prevent misdiagnosis and ensure proper care. Understanding the epidemiology and clinical significance of these organisms in central India is made possible by the identification of particular NTM species.
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INTRODUCTION: Tuberculous meningitis (TBM) is a manifestation of extrapulmonary tuberculosis (EPTB) caused by Mycobacterium tuberculosis (MTB). The central nervous system is involved in about 1%-2% of all current tuberculosis (TB) cases and about 7%-8% of all EPTB. if not treated early, TBM leads to a high rate of neurological sequelae and mortality. OBJECTIVE: This study aimed to assess the diagnostic performance of the GeneXpert MTB/rifampicin (RIF) assay in patients with TBM. METHODS: A total of 100 suspected TBM cases were enrolled from various departments at tertiary care hospital, Bhopal, Madhya Pradesh, India, and classified as definite, possible, or probable TBM. The clinical samples were tested for microbiological and other cerebrospinal fluid (CSF) testing. RESULTS: Out of 100 cases, 14 (14%) were classified as definite TBM, 15 (15%) were having probable TBM, and 71 (71%) were having possible TBM. Out of a total of 100 participants, all were negative for acid-fast bacilli (AFB) staining. Of the 100 cases, 11 (11%) were positive by mycobacterium growth indicator tube (MGIT) culture, of which only four (36.36%) were positive by GeneXpert MTB/RIF. GeneXpert MTB/RIF detected three (3%) cases that were negative by MGIT culture. Ten (90.9%) of the 11 MGIT-positive culture isolates were found to be RIF sensitive while one (9.1%) was found to be RIF resistant. Three cases tested positive/sensitive by the GeneXpert MTB/RIF but negative by MGIT culture. Six (85%) of the seven GeneXpert MTB/RIF positive cases were RIF sensitive while one (15%) was RIF resistant. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were 36.36% (95% Confidence Interval (CI) (10.93% to 69.21%)), 96.63% (95% CI (90.46% to 99.30%)), 57.14% (95% CI (25.50% to 83.85%)), 92.47% (95% CI (88.70% to 95.06%)) and 90% (95% CI (82.38% to 95.10%)) for GeneXpert MTB/RIF assay, compared with MGIT culture as the reference standard. CONCLUSION: Our study found that the sensitivity is lower when compared to culture, so using GeneXpert MTB/RIF alone is not recommended. Overall performance of GeneXpert MTB/RIF assay is noteworthy. The GeneXpert MTB/RIF assay is a potentially accepted test for obtaining an earlier diagnosis, and if it tested positive, the treatment should begin immediately. However, culture must be performed in GeneXpert MTB/RIF negative cases.
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OBJECTIVE/BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is a major public health problem. The diagnosis of MDR-TB is of paramount importance in establishing appropriate clinical management and infection control measures. Rapid detection of MDR-TB allows the establishment of an effective treatment regimen, minimizes the risk of further resistance, and limits the spread of drug-resistant strains. The aim of this study is to determine the genotypic characterization of MDR-TB isolates from extra pulmonary tuberculosis (EPTB) cases in tertiary care centers in Northern India. METHODS: This study was a prospective study. In total, 756 extra pulmonary specimens were collected from patients with suspected tuberculosis in two tertiary care hospitals in Northern India. Specimens were processed for Ziehl-Neelsen staining, culture, and first-line drug susceptibility test using BacT/ALERT 3D system and GenoType MTBDRplus assay for genotypic analysis of MDR-TB. MDR-TB strains were further processed by novel multiplex polymerase chain reaction for rapid identification of Beijing and non-Beijing strains associated with MDR-TB. RESULTS: Of these 164 Mycobacterium tuberculosis complex isolates, 100 (60.9%) strains were fully susceptible and 64 (39.1%) strains were resistant. We noted that the prevalence of MDR-TB among EPTB was 22 (13.4%). The prevalence of MDR-TB was 11.4% in new cases and 19.1% in previously treated cases (p<0.05). Ser531Leu mutation was the predominant mutation noted, and Ser315Thr mutation was more prevalent among the MDR-TB isolates (p<0.05). The proportion of Beijing strains was significantly higher among MDR-TB strains (72.7%, p<0.05). CONCLUSION: The prevalence (13.4%) of MDR-TB among EPTB was high, and the most prominent mutations in rpoB, katG, and inhA genes were S531L (67.3%), S315T1 (94.5%), and C15T (20%), respectively. Beijing stains are significantly associated with MDR-TB among EPTB in this region. We found that the transmission of prominent mutations contributes to an unexpected increase in primary resistance, including MDR-TB cases in Northern India.
ABSTRACT
The occurrence of resistance to drugs used to treat tuberculosis (TB), and particularly multi-drug resistant TB (MDR-TB) defined as resistance to at least rifampicin and isoniazid, has become a significant public health dilemma in a number of countries and an obstacle to effective global TB control. HIV-associated MDR-TB understanding is vital in providing strategies for treatment of HIV and drug-resistant TB. Better understanding on the basis of drug action and resistance is a key to development of diagnostic strategies, novel drugs, and treatment programs, and to find an approach to study the pathogenicity of drug resistant strains. The effectiveness of strategies such as DOTS-Plus in the management of MDR-TB patients under program conditions should be tested in operational field clinical trials following strictly standardized definitions and nomenclature.
